topic Re: regarding PID control in 8-bit Microcontrollers

regarding PID control

ellendula — Tue, 02 Feb 2010 02:34:14 GMT

hello everyone...
i'm working on project, in which i'm using MC9S08QD2 8-bit 8 pin microcontroller.
know i have to implement PID controller for output current of boost converter.
so, please anyone help me how to implement PID using this microcontroller.
so, after searching , i got the paper i.e, AN1215. in that microcontroller it is a 40 orsomething pin and in that registers are defined to store exponennt , mantissa everything....
so in MC9S08QD2 there is nothing like that...
so please anyone suggests me ,
1. how to convert the Digital value of ADC to analog value in the c code
2. how to convert the floating value to the hexadecimal
3. what we have to do , to make recognise the controller that, this is the floating value
4. and finally after the floating point arithmetic , how can we assign the floating value of result to the register.

i require answers for this immediately...
as i have to complete this project soon...
please help me out from this....

thanking you
Shiva prasad E

Re: regarding PID control

bigmac — Tue, 02 Feb 2010 20:37:54 GMT

Hello,

The MC9S08QD2 device does not have sufficient resources of flash and RAM to support floating point calculations. You would need to use a much larger capacity device for this purpose. Even so, the control process will be slow for an 8-bit device, and will limit the ADC sampling rate.

Depending on your sampling rate requirement, you might need to use a 16-bit MCU, or even a 32-bit Coldfire device for this application.

Regards,

Mac

Re: regarding PID control

ellendula — Wed, 03 Feb 2010 01:13:31 GMT

hello ...

i can understand , but i'm using PID for only output current for boost converter.

can you help me...what is the procedure for implementing PID control...if you have any paper or information on PID ...jus send the link, so that i will check once.

for implementing PID , which microcontroller is best...

suggest me, which microcontroller is to be used and provide me some information on , how to implement PID in microcontroller.

thanking you

SHIVA PRASAD